Bio exam 2

• Higher brain functions of the cerebrum

  Cerebrum: is the largest part of the brain and is composed of right and left hemispheres. It performs higher functions like interpreting touch, vision, and hearing, as well as speech, reasoning, emotions, learning, and fine control of movement.

  -is the largest part of the brain and is composed of the right and left hemispheres. which is connected by the corpus callosum.
• Memory consolidation: Short-term vs. long-term

  -Hippocampus: is required for short-term topographical memory in humans. the largest job of the hippocampus is to hold short-term memories and transfer them to long-term storage in our brains.

  -Short-term memory is the capacity to recall a small amount of information from a recent time period. short-term memory is stored in the hippocampus.

  -Long-term memory is the capacity to recall memories from a longer time ago. Long-term memory is stored in the cerebral cortex.
• Long-term memory functions

  -Requires actual structural change: Activation of genes, synthesis of mRNA, production of proteins, and formation of new synapses

  -Nondeclaritive: encompasses non-associative learning, simple conditioning, priming effects as well as motor, perceptual, and cognitive skill acquisition. (the how-to)

  -Declarative: the conscious recollection of experiences, events, and information used in everyday living. can be verbalized
• Different forms of memory

  -working memory: Conscious, active processing of incoming auditory and visual-spatial information, and of information retrieved from long-term memory.

  -Explicit memory: memory of facts and experiences that one can consciously know and declare.

  -Implicit memory: retention independent of conscious recollection. memory you can recall effortlessly.
• limbic system


  -an aggregation of brain structures that are generally located lateral to the thalamus, underneath the cerebral cortex, and above the brainstem. 

  -associated with memory, emotion, and stress response. 
• Emotions controlled by the limbic system

  Aggression: amygdala and hypothalamus

  fear: amygdala and hypothalamus

  Hunger/satiety: hypothalamus

  Sex drive: the whole system

  Goal-directed behaviors: hypothalamus andother regions
• the limbic system and hormones

  -The limbic system influences the endocrine system, the glands that produce hormones that regulate many of our bodily functions. It also affects the autonomic nervous system, which controls some unconscious functions, like thirst, hunger, heart rate, biological clock, or circadian rhythm.

  1. Hunger, satiety, and thirst
  2. Body temperature
  3. sleep and wakefulness
  4. sexual arousal and performance
  5. Emotions of fear, anger, pain, and pleasure
  6. endocrine system
  7. controls hormone secretion from the pituitary gland
• how energy in the environment is converted into action potentials in the nervous system regardless of the type of sensory receptor

  -sensory receptors convert energy in the environment into nerve impulses.

  -Sensory receptors are tuned to both the external world and internal organs.

  -Detecting stimuli such as light, sound, cold, heat, and touch, a sensory receptor sends information to the CNS by triggering action potentials.

  -the brain interprets the intensity of the stimulus from the rate at which it receives action potentials.
• Law of Specific Nerve Energies

  -information from given nerve fiber only experienced as one stimulus type

  -Each neuron that is connected to a sensory receptor can only interpret the stimulus as one thing.

  Ex: the receptors in your retina that deliver action potential signals to your brain can only deliver information about light. The receptors that come from your ear can only deliver information about sound.

  -as long as the stimulus is adequate enough to depolarize, that nerve fiber, your brain will perceive that stimuli as one thing.
• Touch receptors: warm

  -located deeper in the dermis

  -Excited by warming and inhibited by cooling

  -Different from receptors that detect painful heat

  -Near the skin's surface are heat receptors. These receptors allow for sensitivity to heat to be greater in these regions than sensitivity to colder temperatures.
• Touch receptors: cold

  -close to the epidermis

  -Stimulated by cold and inhibited by warm

  -Temperature range of response is 8 to 28°C

  -Cold receptors are sensitive to lower temperatures and are responsible for detecting extreme cold sensations. When the temperature drops below a certain threshold, these receptors are activated, sending signals to the brain indicating the presence of cold stimuli.
• Touch receptors: pain

  -pain receptors are also called nociceptors

  -Sharp pain- myelinated neurons

  -dull pain- unmyelinated neurons

  -Nociceptors activated by chemicals released by damaged tissues,

  pH change, mechanical stimuli

  -Special pain receptors called nociceptors activate whenever there has been an injury, or even a potential injury, such as breaking the skin or causing a large indentation.

  -your brain creates pain
• Touch receptors: pressure

  -the stretching or pinching of skin

  -pressure that affects a graded response

  -pressure can cause the stimulus to depolarize
• Types of Sensory Receptors

  Chemoreceptors: chemicals

  Photoreceptors: light

  Thermoreceptors: temperature

  Mechanoreceptors: physical deformation of receptor
• Tonic vs Phasic

  -A tonic receptor is a sensory receptor that adapts slowly to a stimulus, while a phasic receptor is a sensory receptor that adapts rapidly to a stimulus.

  -tonic receptors continuously generate nerve impulses and slowly decrease the number of impulses relayed to the CNS. Example: pain

  -Phasic receptors generate nerve impulses in response to new or changing stimuli and quickly decrease the number of impulses relayed to the CNS. Examples - smell, touch, temperature
• Lateral inhibition

  -Receptors where touch is strongest stimulated more than areas where touch is lighter

  -Allows well-defined sensations at single location
• Two-point threshold

  -the distance between two points at which an individual recognizes they are being touched by two objects rather than one.

  -The area of each receptive field in the skin varies inversely with the density of receptors in the region.
• How does taste respond to a stimulus and generate action potential?

  -The chemical complexity of taste stimuli suggests that taste receptor cells utilize multiple molecular mechanisms to detect and distinguish among these compounds. Our sense of taste can detect and discriminate various ionic stimuli, for example, Na+ as salty, H+ as sour, sugars as sweet and alkaloids as bitter.

  -taste bud cells depolarize, activate voltage-gated sodium channels, and fire action potentials
• How taste works

  -Salty: Na+ enters taste cell and depolarizes

  -Sour: H+ enters cell and depolarizes

  -Sweet and umami: Sugar or glutamate binds to receptor and activates G-proteins/ 2nd messengers to close K+ channels

  -Bitter: Quinine binds to receptor, activates G-protein/2nd messenger to release Ca2+ into cell
• How smell responds to a stimulus and generates action potential

  1. Odorants are transported into the nasal cavity upon air inhalation where they are detected by olfactory receptor neurons (ORNs)

  2. Stimulation of ORs converts the chemical information encoded in the odorants, into respective neuronal action-potentials which causes depolarization of olfactory sensory neurons.

  3. Smell is processed in the amygdala, hippocampus, and limbic system so a person can recognize and perceive a certain odor

  4. Odor also travels to the prefrontal cortex which helps connect both taste and smell
• How hearing responds to a stimulus and generates action potential

  -The stapes bone vibrates, pushing fluid through the cochlea, which moves the organ of Corti. This motion triggers hair cells, causing potassium and calcium to flow into the cell, firing an action potential. This signal then travels to the brain via the auditory nerve.

  -When sound waves enter scala media, the tectorial membrane vibrates, bending stereocilia.
• How hearing works

  1. Opens K+ channels facing endolymph
  2. K+ rushes in, depolarizing cell
  3. Releases neurotransmitter (glutamate)onto sensory neurons
  4. K+ returns to perilymph at base of stereocilia
• what is the general pathway for taste.

  Facial and glossopharyngeal nerves --> Medulla oblongata--> Thalamus --> Primary gustatory cortex of insula, somatosensory cortex of parietal lobe, and prefrontal cortex
• what is the general pathway for smell?

  Olfactory receptors--> olfactory bulb--> piriform cortex, olfactory tubercle, amygdala, and Entorhinal cortex.

  piriform cortex, olfactory tubercle, and amygdala --> Orbitofrontal cortex, thalamus, and hypothalamus. the Entorhinal cortex --> hippocampal formation.
• What is the general pathway for hearing?

  Vestibulocochlear nerve --> Cochlear nuclei in medulla oblongata & pons --> Midbrain --> thalamus --> Auditory cortex of temporal lobe; Cochlear nuclei and auditory cortex are tonotopic
• Classification of hormones on a chemical level: How does this affect their interaction with cells

  -Hormones cause cellular changes by binding to receptors on target cells. The number of receptors on a target cell can increase or decrease in response to hormone activity. Hormones can affect cells directly through intracellular hormone receptors or indirectly through plasma membrane hormone receptors.
• Classification of hormones on a chemical level: How are they similar and different than neurotransmitters?

  -Hormones can be neurotransmitters in the Central Nervous System.

  -A neurotransmitter is a chemical messenger that carries signals between nerve cells (neurons) in the brain and other parts of the body. A hormone is a chemical messenger that travels through the bloodstream and affects various organs and tissues.

  -Epinephrine. Epinephrine (also known as adrenaline) plays a role in the body's “fight-or-flight” response. It is both a hormone and a neurotransmitter.
• Classification of hormones on a chemical level: How do hormones interact with each other ?

  Antagonistic Effects

  -Hormones work in opposite directions

  Ex: Insulin and Glucagon. Insulin stimulates fat storage, Glucagon stimulates fat breakdown.

  Synergistic Effects

  -Two or more hormones work together to produce an effect

  Ex: producing milk requires estrogen, prolactin, and oxytocin

  Permissive Effects

  -One hormone increases responsiveness to second one

  Ex: Increased secretion of PTH makes intestines more responsive to Vit D3
• Pituitary Gland- Axis between hypothalamus-pituitary-other endocrine(adrenal) glands(HPA axis)

  -The hypothalamus produces several releasing and inhibiting hormones that act on the pituitary gland, stimulating the release of pituitary hormones.

  Hypothalamus --> Thyrotropin releasing hormone (TRH) --> Anterior pituitary --> thyroid stimulating hormone (TSH) --> thyroid gland --> thyroxine (t4 or t3)
• Negative Feedback loop

  -showing how the hypothalamus goes to pituitary gland to endocrine gland. Negative feedback loop reduces secretion.

  
• Pituitary Hormones

  • Growth Hormone (GH)
  • Thyroid-stimulating hormone (TSH)
  • Adrenocorticotropic hormone (ACTH)
  • Follicle-stimulating hormone (FSH)
  • Luteinizing hormone (LH)
  • Prolactin (PRL)
• Trophic hormones

  Stimulate hormone secretion in other glands
• Growth Hormone (GH)

  • Stimulates height, bone length, and muscle growth
• Thyroid-stimulating hormone (TSH)

  • Increases thyroid hormones in your blood
• Adrenocorticotropic hormone (ACTH)

  • Regulates levels of cortisol (stress hormone)
• Follicle-stimulating hormone (FSH)

  • Helps with reproduction, helps women release their eggs and men to make sperm
• Luteinizing hormone (LH)

  • Helps control the menstrual cycle in women, helps men make testosterone by stimulating the testes
• Prolactin (PRL)

  • Responsible for lactation (milk production)
• Hypothalamic hormones

  -Corticotropin - releasing hormone (CRH)

  -Gonadotropin - releasing hormone (GRH)

  -Prolactin- inhibiting hormone (PIH) (dopamine)

  -Somatostatin (Growth hormone inhibitor)

  -Thyrotropin - releasing hormone (TRH)

  -Growth hormone - releasing hormone (GHRH)
• Corticotropin- releasing hormone(CRH)

  -activates due to stress. Its primary function in the body is as the master controller of the hypothalamic-pituitary-adrenal axis, which regulates stress hormones